Topic of the Week

Buoyancy was first understood by Archimedes of Syracuse over two hundred years B.C. Archimedes realized that: “any object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object”. Practically, this can be demonstrated by taking an empty plastic bottle which is sealed with its cap, and placing it in a sink full of water. The bottle sits on slightly below the surface of the water, because the bottle only weighs a few grams. Since the density of water is 1g/ml, you only need to displace a few ml of water to balance the weight of the bottle, so the bottle floats. As you add more and more water to the bottle, you will notice that the bottle sits lower and lower in the water, but that the water line in the bottle is always slightly lower than the water line on the outside of the bottle. Eventually, if your sink is deep enough, you will notice that the bottle does not touch the bot...

Science in the News

On March 2, 2011, astronauts on the US Space Shuttle Discovery attached a new module (called Leonardo) to the International Space Station (ISS). This new module, which was docked to the ISS, will be used for storage. On return...